In recent years, the manufacturers of solid laundry detergent products have focused their efforts into formulating water-soluble laundry detergent compositions that exhibit a good cleaning performance and a good dissolution performance in water. Some examples of these efforts are described in: DE19912679 and WO03/038028, both by Henkel KGaA; EP1416039 and EP1416040, both by Dalli-Werke Wasche und Korperflege GmbH & Co. KG; and WO05/083046, WO05/083048, WO05/083049, WO06/020788, WO06/020789, WO06/088665, WO06/088666, EP1690921 and EP1690922 all by The Procter & Gamble Company.
However, the Inventors have found that water-soluble laundry detergent compositions are susceptible to significant variations in their cleaning performance depending on the dosage used by the consumer during the laundering process, especially under conditions such as soft water and low wash water temperatures, and especially when the detergent composition comprises bleach and/or polymer. Due to the difficulty of accurate dosing, consumers often significantly under- or over-dose their laundry detergent products during the laundering process. Therefore, there remains a need for a solid laundry detergent composition that is highly water-soluble and consistently delivers an excellent cleaning performance, especially an excellent stain-removal performance and whiteness maintenance performance, across a wide range of dosage habits.